Behavior: Submits a media builder render job that combines multiple assets, overlays, and effects into a single output media file. The rendering occurs asynchronously.

Authorization: Requires a valid Bearer token.

Side Effects: A media rendering job is created and processed asynchronously. The resulting output file will be created as a new asset upon completion.

Error Scenarios: Returns 400 if the request body is missing or invalid. Returns 401 if the caller is not authenticated. Returns 404 if the input model is null.